Sub-Select Using LinqToExcel

Question

I'm trying to figure out how to perform a sub-select using Linq. I have an excel sheet with a 'debit' and a 'credit' column. I need to filter out any rows which have a debit column value (> 0.00) that matches up with a credit column value further down. Both rows must have the same payer id. Here's what I have come up with so far:

    public void balanceSheet()
    {
        foreach (Payment payment in this.payments)
        {
            // c[6] is the payers ID.
            var debits = from c in this.test.WorksheetNoHeader()
                         where c[6] != "0" && c[13] != "0.00" 
                         select c;
            // Find any rows in the sheet that have the same payer id AND the debit 
            // amount from the query above in it's credit column.
            foreach(LinqToExcel.RowNoHeader debit in debits)
            {
                var credits = from c in this.test.WorksheetNoHeader()
                              where c[6] == debit[6] && c[15] == debit[13]
                              select c;

                // Do something awesome if it finds something.

            }
        }
    }

I'm hoping there's a way more elegant solution to select excel rows by the criteria above rather than looping through them each time. I don't think I am using LINQ to it's full potential here by any means. Any ideas?

Answer 1

LinqToExcel doesn't support joins, but you can convert it to an in-memory list and then perform the join

var credits = from credit in this.test.WorksheetNoHeader().ToList()
  join debit in this.test.WorksheetNoHeader().ToList() on credit[6] equals debit[6]
  where debit[13] != "0.00"
  where debit[13] == credit[15]
  select credit

Answer 2

Try a join:

var credits = from credit in this.test.WorksheetNoHeader()
  join debit in this.test.WorksheetNoHeader() on credit[6] equals debit[6]
  where debit[13] != "0.00"
  where debit[13] == credit[15]
  select credit

For more information: http://msdn.microsoft.com/en-us/library/bb311040.aspx